fluminum
fluminum is a Latin form of flumen, meaning “river”. It is the genitive plural neuter noun.
Found 66 times in the Latin texts on Socratos.
Where it is used
Caesar, De Bello Gallico 6.30.3: quod aedificio circumdato silva, ut sunt fere domicilia Gallorum, qui vitandi aestus causa plerumque silvarum atque fluminum petunt propinquitates, comites familiaresque eius angusto in loco paulisper equitum nostrorum vim sustinuerunt.
Aulus Gellius, Noctes Atticae 10.7.a: Fluminum, quae ultra imperium Romanum fluunt, prima magnitudine esse Nilum, secunda Histrum, proxima Rodanum, sicuti M. Varronem memini scribere.
All forms of flumen (declension table)
Source: Socratos (socratos.org), a free reader for Ancient Greek and Latin. Grammar from the Perseus Treebank and Morpheus; dictionary entries from Lewis & Short, A Latin Dictionary (Perseus Digital Library, CC BY-SA). Counts are from the texts on Socratos.